Evolution of variant allele frequency of dominant mutations in responders and nonresponders to lenalidomide after short-term treatment. (A) Variant allele frequency of each major mutation was shown before (0 cycles) and after 4 cycles of treatment in responders (n = 20; left) and nonresponders (n = 22; right). (B) Variation of variant allele frequency was calculated as follow-up minus screening for each responder and each nonresponder. Box plots represent medians and IQRs [25%–75%], and whiskers extend to 1.5 times the IQR. Variations are compared between responders and nonresponders using the Mann Whitney U test.